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The Diet Advice You Can’t Ignore

I’m proud of my university degree at UTAS.

The Medical School is small, a mere 70 students a year, with some years dropping to 60 (illness, pot smoking, or tree hugging dependent – hey, don’t judge, it was Tassie remember!). But one aspect of my training has influenced me permanently. What UTAS did well, was foster our ability to critique medical information. To expose fact from fiction, enabling us to form robust treatment opinions based on evidence… REAL evidence.

Importantly these philosophies, ethos, and methods were echoed by all our influential lecturers, at every stage of our training.It means I’m an evidence based practitioner. I make the hard decisions for you – do we or don’t we treat, what drugs do we use, based on evidence… REAL evidence.

Ten people living in a tent for a week eating mandarins and not getting measles is not a robust trial. 20,000 people eating mandarins and 20,000 eating pretend ones all matched for a bunch of stuff like age, sex, other diet, medications, and vaccinations (plus even more stuff that the geeks get excited about) IS a robust trial.

Social media is full of endorsements for weight loss strategies, from major campaigns like CSIRO, through Michelle Bridges and her 12 week thingo, there’s the Atkins and 5-2 diets, to name but a few. We are even seeing our sacred nightly news bombarded by wishy-washy reports into various options.

Today, I want to answer the question – which is best? And, maybe even – do they work?

These popular weight loss strategies combine varying components of dietry and lifestyle recommendations with diverse delivery methods – books, online apps, or in-person. Each strategy will have a central philosophy, usually quite diverse from the others, pro-porting specific advantages with restriction or indulgence in various micro or macro nutrients: maybe low sugar, high protein, low GI, low fat, or the ridiculous superfoods.

As the punter wanting to start a weight loss program there is little information available. This means its hard to decide which one is better than the other, with readily available evidence lacking to back that decision up. This results in the bigger flashier advertising budgets generally winning out.

PLUS, not all of the information we read about individual weight loss strategies is based on robust medical research ie it may work in some, but not necessarily across a large population.

This year, the JAMA (The Journal of the American Medical Association), one of THE biggest, best, and most prestigious medical research organisations released an incredibly valuable Meta-analysis into weight loss strategies. Basically, they pooled a whole bunch of robust medical research studies (59 articles from 48 unique randomised trials in 7286 individuals), and applied further robust statistical and appropriate analyses, to determine weight loss outcomes. ie Do they work.

They looked at the following diets:

  • Low carbohydrate – Atkins, South Beach, Zone
  • Moderate macronutrients – Biggest Loser, Jenny Craig, Weight Watchers, LEARN
  • Low Fat – Ornish, Rosemary Conley, LEARN

The geeks worked their magic and accounted for various parameters such as calorie/kilojoules restriction, exercise, and the degree of behavioural support, plus, they looked at follow up timeframes.

So what did they find out?

You can check out the entire meta-analysis here, but I want to draw your attention to the main points:

  • Both low-carbohydrate and low-fat diets were associated with an estimated 8kg weight loss at 6months compared with no diet.
  • Approximately 1-2kg of this was reversed at 12months. ie you need to maintain the eating plan.
  • The differences between diets were SMALL.
  • If the diet reduces the energy you eat, then you lose weight! NO MATTER HOW YOU REDUCE ENERGY INTAKE!
  • Behavioural support and exercise enhance weight loss.

The beauty of this meta-analysis is that it brings robust evidence to the fact that most diets work, and the best one for you is the one you’ll stick to!

So get out there, eat less, exercise more, and find someone to kick you in the bum to keep you honest.

Dr Sam.

19SEP14